Electrically operated remote controlled rear view mirrors mounted on either the left or right side of a vehicle are an accessory found on automobiles. In the typical arrangement, a mirror is mounted on a support member which is pivotally mounted on a base member or housing. The housing is in turn mounted on either the left or right side of the automobile. The support member moves relative to the housing in the horizontal and/or vertical directions. Extending between the housing and the support member are a pair of linkages for pivoting the support member. A pair of reversible driving motors are mounted on the base member and each motor actuates one of the linkages. The motors are controlled by a switch operated by the driver. Examples of this type of remote controlled mirror are disclosed in U.S. Pat. Nos. 3,609,014 and 4,611,401.
Even though electrically operated remote controlled rear view mirrors are convenient, it is more desirable to be able to program a computer or computer module to remember a preset position of the mirror for each driver. The position sensor system for controlling the position of the mirrors is typically used in conjunction with a system for controlling the position of a driver's seat. Upon pressing a single button, a driver may automatically reposition the driver's seat as well as both the left and right outside rearview mirrors. Position information for the seat and both mirrors are programmed into the computer module.
In order to be able to program in memory the position of the mirror there must be a mechanism for sensing the position of the mirror along the horizontal and vertical axes. Presently, mirrors use linear motion potentiometers for determining the position of the mirror. The potentiometers are linearly displaced by the motion of the mirror in either the horizontal or vertical planes. A fixed voltage is impressed across the potentiometer and a portion of the voltage is tapped off by a sliding member of the linear motion potentiometer to be used as an input signal. This input signal is sent to a computer where it is processed and stored. The level of the input signal corresponds to the physical position of the mirror.
These potentiometers have been troublesome in that they are subject to mechanical wear, subject to mechanical failure of the slider contact due to contaxination from salt, dirt, and dust, and are expensive to replace. Potentiometers, because of their mechanical nature, may suffer from poor resolution and backlash. This can lead to improper mirror positioning.
To solve these and other problems, the inventor herein has succeeded in replacing the linear motion potentiometers with electronic position sensors which have no moving parts in contact with one another, are not subject to mechanical wear, and are not subject to contamination due to salt, dust, or dirt. The invention includes a means for indicating the position of the mirror relative to its mount comprising a member associated with the mirror, combined with means to sense the member's position comprising an inductive winding, or an oscillator. The invention is illustrated by providing an assembly with electronic sensors each comprising an inductance coil into which is inserted a tapered steel rod. The coil can be part of a Colpitts oscillator. When the steel rod moves through the coil it absorbs energy at a varying rate, causing the A.C. output voltage of the oscillator to change in relation to the position of the tapered rod in the oscillator coil. This output voltage is amplified, converted to a D.C. voltage signal, amplified again, and then outputted to the computer. Drive means responsive to the indicating and sensing means moves the mirror to its position.
The following set forth objects of one or more of the claims for the invention. It is an object to provide an assembly to adjust the position of a mirror of an automobile to selected preset positions relative to the mount for the mirror by a member which is associated with the mirror and is electromagnetically associated with a sensor.
It is further an object to provide a means for sensing the position of the member relative to the mirror mount. Furthermore, it is an object to provide a means for indicating and sensing the mirror position comprising an oscillator and an indicator member, with means for electromagnetically controlling the electrical output of the oscillator upon movement of the indicator member. It is further an object to provide a means for sensing the position of the member which comprises an inductive winding electrically associated with the member.
An objective as well is to provide a drive means responsive to the indicator and sensor means, which moves the mirror to the desired position.
An additional object is to provide an assembly with a position indicator comprising a member capable of absorbing electromagnetic energy. Moreover an object is to provide such a member which has a varying cross section.
Further an objective is to provide such an adjustment assembly wherein the means for indicating the position of the mirror is a rod comprising metal having a longitudinal taper, and wherein the sensing means is an inductive winding positioned so that the metal rod can be moved to be surrounded by the winding. It is an object to have the tapered part of the rod to be of a substantially conical shape.
Another object is to provide a means of generating a voltage or signal output in such a system which is a mathematical function of the position, or of the travel, of the member and which thus acts as a position sensor.
Still another objective is to provide an electromagnetic sensor using an oscillator and a differential amplifier means, and a means for converting from alternating current to direct current.
It is moreover an object to provide such an automotive position sensor which does not employ linear potentiometers.
Yet another object is to provide an automotive position or travel sensor which minimizes problems caused by frictional wear, and which resists failure caused by contamination from salt, dirt, or dust.
Another object is to provide such an adjustment and positioning assembly which eliminates inaccuracy due to noise and interference which is present with potentiometers used for such positioning and adjustment.
It is further an object to provide proper resolution of an image in a mirror which has its position adjusted on an automotive vehicle.
Yet another object is to provide a position or travel sensor comprising a self-excited electronic L-C oscillator which features a flat spiral wound inductive coil as a component of the resonant tank circuit, into the center axis of which is inserted a steel rod, the shape of which determines the position output function.
An objective is to provide a position sensor which when used in pairs can position an automotive rear view mirror in each of two planes and provide voltage outputs that are proportional to the mirror surface position.
It is furthermore an object to provide a position sensor for an automobile mirror which can be used with a computer memory seat system to control the portion of the seats and of the mirror.